Audio system



FIG. 1 is a front perspective view of an audio system showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof, the right side view being a mirror image thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines represent unclaimed portions of the design and form no part of the claimed design. 

CLAIM The ornamental design for an audio system, as shown and described. 